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This study was approved by the institutional review board of Partners HealthCare (Massachusetts General Hospital, Boston, MA, USA) number 2012P002313, the National Institute for Medical Research (Dar es Salaam, Tanzania) number NIMR/HG/R.8c/Vol. II/297, and the MoH of Tanzania (Dar es Salaam, Tanzania). Verbal consent to participate was sought and granted by the IRBs on the basis that the study represented no more than minimal risk of harm to subjects and involved no procedures for which written consent is normally required outside the research context.

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Not applicable

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The authors declare that they have no competing interests.

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